Aerator for flotation ore separators



Sept. 13, 1927.

H. WALL AERATOR FOR FLOTATION ORE SEPARATORS Filed July 2s. 1925 2 `Sheets-Sheet. l

snr-naman Sept. 13, 1927.

1,642,051 H. WALL j AERATOR FOR FLOTATION ORE SEPARATOR-S-A Filed Jun/2s, 192.5 2 sheets-sheet 2 rma sa.. 13,1921.. 1,642,151.

' barren .smi-ss PATENT 'oFFlCa annonnwnr., or sur un'. crrx, man.

Ammon ron rno'rarioii can summons. Appunti mamy-as..` im.' man I. cesse;

This invention relates to aerators suitable for use, for example, in flotation ore separators, wherein mineral particles are separated from the rock or gangue of the commia nuted ore by-causing air bubbles to rise through a mixture of pulverized ore or pnl water, oil and acid, the rising air ub les carrying upward the mineral particles and forming a froth, retaining the l mineral particles, at the top of the mixture.

Heretofore the common practice has been to form the bubbles by forcing air through a mat of heavy textile fabric lying upon an inclined pan or bed near the bottom ofthe l separator cell while the pulp mixture flows through -the cell over the mat, to cause the air to be extensively distributed under the pulp and to rise therethrough in the form of small bubbles.

An undesirable feature of the fabric mat is that the oil and acid of the pulp mixture causes it rapidly to deteriorate and it frequently becomes clogged, especially with oxide of iron .from the plulp, and requires to be beaten to vfree it of t eA Odged material so that it will function uniformly throu hout its extent. The fabric mat alsoA requently becomes broken or pervious to the pulp, with Athe result that when the air is 30 shut oi the pulp'mixture, ows into the air line, clogging the latter with sediment,

and requiring much time and labor to clear 20 by vulcanization throughout the said im,

itfor further operation.

My chief objects are to provide an improved aerator having great durability,

especially iinder conditions of use in a otation ore separator, to provide an aerator adapted eifectively to prevent the flow of a pulp mixture or the hke into the air ipe C0 or pipes when the air pressure is cut o to provide for a uniformdistribution of the air substantially throughout the extent of the aerator, and to provide an aerator adapted for long continued service without diicult or expensive treatment to keep it in serviceable condition.

Of the accompanyin drawings, Fig. 1 is a longtu inal vertical. section of anore separator. cell, and myimproved 5" aerator in place therein.

Fig. 2 is a fragmentary perspective view of my aerator, part being broken away for clearness of illustration.

Fi 3 is a section on lined-3 ofvFig. 2,

u cna arger 01.21%. 4; is a section similar to Fig. 3-of a m ed form of aerator.

Fig. 5 is a section on line 5-5 of Fig. 3. .Fig 6 is a vertical section of a modiication.

Referring to the drawings, 10 is a rectangular ore separator cell provided with the usual spillway 11, pulp-inlet chute 12, liquid-level control ipe 13, and gangue outlet conduit 14. y improved aerator, generally designated 15, is mounted above the bottom of the cell just below the pulp inletV 12, upon suitable bracket supports such as th e one shown at 16, said supports being inclined downwardly from said pulp inlet toward the opposite end of the cell above, the

gan e out et 14: For supplying airlocally to t e aerator, air pipes or hoses 17, 17 con-f nect with the same from below, said pipes leading from an air manifold 18 provided with a shut-off valve 18 and adapted to 'receive compressed air from av centrifugal blower 19. A

flhe aerator 15 comprises a flat, relatively thick slab or bed member of hard rubber 20, and a rubber mat 21 mounted thereon, said mat being formed with a multiplicity of small perforations 27 27 substantially throughout large zones thereof defined by imperforate marginal 'z'ones 122, 22 and transverse imperforate zones 23, 23, and being secured to the hard rubber slab or bed perforate zones, so that air forced through oneof the (pipes 17 intol the space between the bed an one of the perforate zones can escape only throughv the perforations of that zone.-

,. Substantially at the middle ofeach per- `forato zone the mat 21 is formed with van o5 mtegral, upstanding, hollow cap'24, which -covers lthe u per end of a. tubular metal nipple 25, mol ed into the bed 20 and projecting from each face of the latter, the lower end of said nipple being connected with the Inn respective pipe 17. At the base of each cap 24 the sheet 21 is formed with an im r l rather extensive val)e forate, concentric, lar zone 26, which is preferably suilciently thick adjacent the ca to prevent the sheet 105 21 from excessively or flexing at the base of the cap when the latter is urged upward by incoming air from the nipple 25. The valvular zone 26 is adapted to seal against thebed 20 when the air supply is 110 lil I mat.

stopped, substantially to prevent a return ilow of pulp mixture. The cap 24 is formed with internal, vertical ribs 24', 24* adapted to bear against the nipple to prevent und-ue inward flexing of the vertical wall of the cap under the force of the pulp mixture when the air is cut off. The u per or end wall 24 of the cap' is iexible an isadapted to-be lifted by and to permit the passage of compressed air forced upward through the nipple and to be pressed downward and to close the mouth of the nipple to prevent a return iow of air when the air supply valve 18* is closed. v

The .perforations 27 are arranged in par allel rows longitudinal] and transversely of the aerator, each per eration being' frusto-conical in shape with its small end opening onto the upper face of the sheet 2l. Each perforation is connected with adjoining perforations by longitudinal grooves such as the one designated 28 and transverse ooves 29, 29, in the lower face of themat, lili 3, said grooves being adapted to 'distri ute air evenly from the inlet pipes 17 to the various perforations notwithstanding the fact that portions of the sheet 21 may be pressed tightly against the su porting slab 20 by the overlying pulp. y invention, however, is not wholly limited to the presence of such grooves. The grooves 28, 29 do not intersect the cavities within the res ctive caps24, the lower face of the zone 26 eing smooth and fiat and adapted to act as a self-seatingr valve, except as its operation may be afected by grit, to prevent return flow of fluid into the nipple 25 when thesupply of compressed air is stopped.

The aerator is preferably constructed of an abrasion. resisting rubber com ound and one 'of such characteras not to e affected by oil, acid, or oxidized iron', so that a relatively long period of usefulness is obtained.

In the operation of my apparatus, the pulp 30 being caused to fiow through the cell l() in the usual manner, air is Jforced through the nipples 25 into the spaces between the perforated zones of the mat-and the bed member `20, the hollow caps 24 being lifted by the air pressure, against the weight of the overlying pul and the air escapes through the perforations 27 of the The grooves 28, 29 insure a substan- ,tially uniform distribution of the air to the various perforations even though the air pressure is not sufficient to raise the per# forated Zones of the mat from the bed 2() throughout any or all of their extent.

The conical shape of the perfor-ations 27 results in the formingof very small air bubbles and alsok avoids clogging of the perforations. The walls of the perforations being elastic, the perforations vary in size `with variations of the air pressure, enlarging as the air pressure increases, admitting air to the pulp mixture with a spray efect which is contributed to by the resihence o the elastic aperture walls, with the result that very fine bubbles are roduced both when `the air is forced rapi ly, with high pressure, through `the enlarged holes and when the air under less pressure is forced more slowly through the holes with the 1atter in a less dilated condition;

The weight of the pulp mixture within the cell presses the base 26 of the cap and other parts of the mat upon the supporting slab 20 when the air pressure Within the nipple 25 is less thansuiiicient to support the column of pulp mixturez as in case of air leakage or in case of an increase in the height of the column, a sealthus being effected between the mat and the bed member to prevent flow of pulp into the air line. Under the same conditions also the upper 0r end wall 24" of the cap 24: .is pressed" downward bythe ressure of the' ulp mixture and closes t e mouth of tb against return flow of air, even though the valvular zone 26 should fail to function perfectly.

It will observed that since the nipple- 25 rises to a. substantial height above the bed 20, none of the' fluidy containin the `gritty pulp can enter the nipple untll all of the air external to the nipple within the cap has been forced back thereinto, and that if such return flow of air be prevented, either by described closing of the mouth of the nipple or by air pressure within the nipple, the return iow of fluid is limited by an overlying layer of entrapped air.

Such an overlying layer of'entrapped air may be provided by the use of the upwardly projecting nipple 25 and the enclosing cap 24 without the aid of the sealing effect of the ca s end wall 24 or the valvular zone 26, 'an if the volume of entrapped air within the ni ple and its supply connections be made su ciently small, as by positioning shutoff `valves closeA to the nipple, as 1n the modification shown in Fig. 6, the increase of air pressure within the nipple incident to forcing the external air back thereinto will be so great as not to be brought about by even a very great increase of head in the liquid, as in filling the'cell at the beginning of operation. This will readily be understoodupon consideration of the fact that if the entrapped air were of equal volume on the two sides of the nipples mouth, and were at atmospheric pressure, the forcing of the external air back into the nipple would increase the` pressure therein to two atmospheres, so that the liquid would be subjected to a pressure differential `of. one atmosphere, which is suicient to support a column of the pulp mixture many feet in height.

Such high pressure within-the nipple is e nipple Lemon of not relied d d the'. cl vanaaf,

action of the cav s en wall 29 is employed,

. action'ealls` for greater.;

lluidtplressure upon; the liquid side than upon Y. am marisa of liquid toward the, mouth of Y 6, where the valves'are dted'18b`,

thenipple is by an overlying layer' of entra adr. WhenpptliiiA shut-olf valves arel rovided closely adjacent the nipple as own in 18, the are provided with actuating means ada Y to be operated Yfrom the exterior prises a valve-actuating rod enteringthe cell through a suitable gland 36 and having l `-blocks 37, 3'( slidably mounted thereon and having stud-and-slot connection with the respective valve levers '38 38. In order that all of the valves may be firmly-closed by the' same rod each block is mounted to yield b sliding upon'tbe rod and is backed on eaych side by a compressionjsprmg .39,

.mounted u n the rod and seating againstJ a'collar 40Posecured on the rod, solthat'if v one valve seats slightly before another, be-

I sheet 21, upon the sup cause of inequalities of construction or adjustment, the rod may nevertheless be moved' somewhat farther', to seat the other,A valves.4

In the modification shown in Fig. 4, the rting bed '20,. is formed with perforations inthe shape of slots 31,31 disposed at right angles Vto'eacbother and having-inclined side andeend walls to form relativel smll elongated apertures in the top sur aceof the bed member. The

I slots 31 are ada ted to sprayine sheets of air into the p p mass, said sheets intersecting over eachA other so as more inti` mately to mix with and a tate sald'mass.

In my aerator as descri I prefer to em' ploy a bed of4 plane form, as the rubber mat functions better therewith, but my invention is not wholly limited thereto.

' from solid The mat may readil be freed ged in its perforations by flexing matter lod and stretching of the mat.

be resorted to Various modifications may v without departing from the scpfe of my invention asdened in the appen ed claims.

I claim; `1. The combination, with a flotatlon oreseparator cell, of an aerator therein, said aerator comprising air distributing means and means for conducting air thereto, the last said means comprising a device adapted to prevent areturn low of liquidby opposing to the liquid an overlying layer of entrapped air.

2. An aerator comprising a bed member,

an air-supply nipple ,projecting upwardtherefrom, and a perforate mat lying upon said bed meinber and formed with an 1mperforate cap portion surrounding" said nipple.

e air side of the valve,'but in either e cell. The means here shown com' to prevent a Y conduit:

"a, .in-'mim de definedin claimed@ which the cap h 4. Anvaerator as defined in claim 2 in which the cap portion of the matis adapted to seal against the bed member about the base of the nipple. l

5. An aerator .as which the cap portion of the mat is adapted ram of thema-is ada to act as 'a v ve against the mouth o "nipple..

defined in ciaima'in to seal against the mouth of the nip le and .also against the bed, member about t e base of the nipple.

6. An aerator comprisingk a bed member, an vairconduit havin a'discharge orice in communication wit the upper face of said bed member, and a perforate mat lying vupon said bed member and having an im-v to permit air to pass from said conduit into the space between said Vbed memberl and the perforate vportion of the mat but return ow'of fluid into vsaid 7. Th' combination,.with a flotation oreseparator cell, of an aerator comprising a bedmember, an air-supply conduit communi- A eating with the upper face of the said bed member, .and a perforate -rubber mat lying u n said bed member and formed with airvpervious portion adapted Yto act as a valve -s's j dlstributing channels in.4 its face adjacent the bed member.

8. A flotation ore-separator comprising a dcontainer for the ore mixture and an aerator Y therein, said aerator comprising a rforatc rubber mat, a bed member under ying the mat and an air conduit leading to the space between the two, said mat having an iml perforate portion ,and said conduit having a terminal portion projecting upward from the face of said bed member and adapted to be sealed bythe imperforate portion ofthe mat in the manner o a valveito prevent /areturn flow' of liquid into said conduit when thev current of air in the latter stopped.'

`9.' An aerator comprising a bed member, perforate rubber matting lying thereon and sealed thereto in zones defining segregated Aareas of the perforate' matting, and indi# vidual pipes adapted to conduct air into the respective spaces between the said areas and the bed memberthe said bed member underlying theA said matting and being' substantially without downward fomated rubber mat' lying thereon, and means for forcin air between the two, the bed member an the mat being so con structed that the mat will seal against the bed member when the current of air is stopped and prevent the overlying material from owing backward through the perforations of the mat.

11. An aerator comprising a bed member,

10 a perforated rubber mat lying thereon, said man being formed with ldistribuer@ Chan-.

to coact as a valve in sealing thelower.

mouths of the perforations and distributing channels to prevent a return flow between the bed member and the mat.

In witness whereof I have hereunto set my hand this 6th day of Jul 1925. l HARO D WALL. 

